Indium-tin-oxide (ITO), also known as tin-doped indium oxide, is a transparent conducting solid often used as a thin-film coating in applications where radiant energy, especially light, is coupled into a substrate that is provided with electrical contacts. For instance, devices such as flat-panel displays and smart windows rely on ITO coatings to carry electrical signals across the surface of a glass substrate while allowing light to pass through. In some applications, such as flat-panel displays, it is necessary to make patterns in conducting ITO coatings in order to fabricate separate conducting signal lines from the initial continuous ITO layers.
Insulating patterns are generally formed by photolithography combined with either wet chemical etching or plasma etching, which removes the ITO coating from selected regions. This has disadvantages, one of which is the resultant raised pattern of conducting ITO, which is less suitable for deposition of subsequent coatings and more susceptible to physical damage than is a smooth, contiguous area. Therefore, it is desirable to form insulating patterns that have the same thickness and are contiguous with the conducting ITO patterns.
Moreover, these conventional methods tend to generate relatively large quantities of corrosive, environmentally unsafe, and/or otherwise hazardous by-products. Therefore, it is desirable to form insulating patterns via methods that generate relatively safe, non-hazardous by-products.
For further information, refer to the following publications:
1. J. Haisma, et al., "Resistance Modification of Indium Oxide Layers by Laser Annealing and Ion Bombardment Respectively", Philips Journal of Research vol. 41, p. 77 (1986). PA1 2. T. Serikawa, et al., "Studies of H.sub.2.sup.+ Implantation Into Indium-Tin-Oxide Films", Nuclear Instrumentation Methods B vol. 37/38, p. 732 (1989). PA1 3. Y. Shigesato, et al., "Study of the Effect of Ion Implantation on the Electrical and Microstructural Properties of Tin-Doped Indium Oxide Thin Films", Journal of Applied Physics vol. 73, p. 3805 (1993). PA1 4. Y. Shigesato, et al., "Laser and Ion Beam Modification of Materials", Proceedings of the 1993 International Conference on Advanced Materials, I, Yamada, et al., ed. (1994). PA1 5. T. E. Haynes, et al., "Donor generation from native defects induced by In+ implantation into tin-doped indium oxide", Journal of Applied Physics vol. 77, p. 2572 (1994). PA1 6. S. Pongratz, "Info highway will be viewed on flat panel displays," R&D Magazine, p. 27, April 1994. PA1 a. providing a substrate having a conductive ITO coating on at least one surface thereof; PA1 b. rendering a preselected portion of the coating of conductive ITO insulative, leaving the remaining portion of conductive ITO as at least one electrical pathway.